Contents

At the start, you can see two openings. Take the one on the left, and open the door inside. Go in, and grab the shotgun shells to your right. Then turn around, and follow the hallway to two doors. One of them leads to four teleporters.
Go through that door, and walk on the teleporter. When you get warped to a new location, a door will open, and the room has power-ups, and a demon or baron (depending on the skill level). Go in the room the enemy came out of, and grab the goodies (this will add to your secrets percentage). In each corner of this room is a teleporter. Take the teleporter in the northwestern part of this room (use the automap to find the exact teleporter).

In this new room, kill all the enemies here. Heal yourself with the medikits in here too. Also in this room are two doors next to each other. Take the one on the right. Go into the room, and follow the hallway to a red pillar. Walk through it from the south end, and then the wall in front of you will lower. Go into this room. In this room, there is a crushing pillar in each corner of the room with a switch behind it. Hit the switch under the northeast pillar, and then in the northwest part of the room, a platform will lower, containing the blue key.
Now, behind the southwest pillar in this room is a teleporter. Go through it (the pillar locations are from the entrance of the room).

Now, you are in this familiar room again. This time take the left door. Follow this hallway to the Blue Door, killing any imps or lost souls in your way. Go through the blue door, go left, open the exit door, and go through the exit teleporter.

You may optionally take the skull-covered door to the right of the exit. In the right of the room behind it, you can find a BFG 9000 in the eastern alcove. However, firing any weapon in this room will cause a large number enemies to teleport into the area. Hence it is best to try to avoid the single Imp in the room, that's acting as bait, rather than killing it.

In the starting area, take the door on the very left (the door well-lit by the torches). Open the wall on the left in the following room to get a pair of light amps.

On the west side of the map is a wide corridor lined with a series of red brick columns. There is a door on the west wall; continue through to reach a not-so-secret area with a soul sphere and plasma rifle.

In the northwest of the map there is a bright red room with damaging floors. On one of the walls here is a pair of blue symbols. Open the section of wall between them to get a radsuit.

Take the teleporter in the aforementioned red room. You'll be taken to the center of the courtyard. The southern of the four structures surrounding the center teleport will have opened, and contains a yellow skull key.

With your newly acquired yellow key, make your way to the east end of the courtyard. There is some glowing red "writing" high on the wall. Open the wall below and slightly to the right of the symbols to get a chainsaw and another soul sphere. To exit the courtyard, take the teleporter in the northwest.

From the room you end up in after exiting the courtyard, go through either door, then the door next to it on the other side. Walk through this teleporter and you'll be taken to the courtyard center again. The structure north of the central teleport will open up; inside are some goodies.

In the north of the map is a corridor shaped like an upside-down "U". Search the outer walls on the western side of this corridor. One of them will open, leading to a secret area overlooking the bright red room from earlier.

At the north end of the map is a red brick room with four crushers guarding switches (the blue skull key is in this room as well). Press the switch in the southeast crusher and three alcoves will open on each side of the room. The one containing a rocket launcher (the middle one on the east side) counts as a secret.

Go through the teleporter in the southeastern corner of the courtyard from one of the doors inside the building (i.e. not from the courtyard itself). Like secrets 4 and 6, one of the structures surrounding the central teleport will open up; its inside counts as a secret.

Same as secret #9, but use the southwestern teleporter. Again, you must enter from inside the building rather than the courtyard.

Six "hanging leg" decorations (Things 224-229) have no flags set for any of the difficulty classes, so they do not actually appear in the level. Things 228 and 229 are placed on top of one another as well.

The trigger to open the northernmost room is also supposed to lower a sector with a tag 8. No sectors with this tag appear on the map.

In the northernmost chamber there are three crushing pillars, each of which protects a button. However, it is not necessary to step under an open pillar to get a switch hit. This is due to an engine limitation that, in this case, allows the player to trigger the buttons from the edges of their walls, while standing safely outside of the pillars. The event is possible even if the crushers cover the switches at the moment they are clicked.

At secret number 7, there are two linedefs that are supposed to also raise the jagged gate ceiling to the entrance of the northwest room of the map. However, you need to walk on them to trigger it, and they are part of a wall structure.

The door leading to the BFG starts below the nearby floor. When raised, there's two sidedefs visible with no lower texture, allowing a minor graphical glitch. Whether the door itself should be lower than the nearby sectors is debatable.